Adam Carter finds himself hunting for a onetime friend, Richard Dempsey, when Harry Pearce orders the man assassinated. Dempsey was once an agent but apparently went over tot he other side during the Bosnian war. He was present when Adam was captured and brutally tortured and since has become an assassin. A top Serb commander Niko Grecic is under MI-5 protection after he turned in the notorious Serb General Marko Tezila and will be testifying against him at the upcoming war crimes trial in Brussels. When they learn that Dempsey is in the UK, they are sure he is there to assassinate Grecic. When Adam finally catches up to him, he has a different story to tell, sending them all off in a completely different direction.
- When two MI-6 officers are murdered in Hungary, all evidence points to rogue agent Richard Dempsey, who has links to Serbian war criminal, Niko Grecic. As Grecic is now in Britain and scheduled to give testimony in a war crimes trial in The Hague, MI-5 must protect him from an assassination plot that appears to emanate from Dempsey. Adam's (Rupert Penry-Jones) grief and his past with Dempsey-who is not only a childhood friend but was also present when Adam was captured and tortured during an MI-6 op in Serbia-interferes with the operation and Harry (Peter Firth) orders the team to take extreme measures to stop Adam's interference and eliminate Dempsey.